Spanning Tree Priorities

[PhilUK]

Hi,

We have several 3400cl’s used for our LAN infrastructure which are setup with multiple trunks for resilience.  These trunks are setup with different spanning tree priorities to manage were the ports are blocked.  We are running on 7 VLANs.

We are implementing a new RF infrastructure (WLAN) in our warehouses and are using POE 2520’s in a fibre ring configuration.

I will need to connect the new WLAN to the current LAN in two places (again for resilience) and I’m unsure of the spanning tree priorities to set.

I have attached a diagram with the showing current LAN spanning tree priorities and how I’m planning to connect the new WLAN.  The Pn values in red are the suggested priorities.

Can anyone offer some advice on whether this will be ok, or is there a better way of connecting the WLAN to the WAN?  Maybe I should make the connection between switches WLAN5 and WLAN1 a higher priority?

Thanks

[Richard Brodie_1]

To a first approximation, you are wasting your time setting port priorities (if that's what you are doing).

The important information is which is your root bridge, and what are the path costs? Which will be the root in the combined network?

Whilst your diagram is clear, its pretty much impossible to tell what effect changing path priorites will make, and it's quite possible it will make no difference at all. Path priorities can be useful as a tie-breaker but you might not have any ties.

Secondly, do you have any particular constraints in mind; do you care which links are down in normal operation?

[paulgear]

I agree with Richard. I think it's much more helpful to set switch priorities in this scenario than it is to set port priorities.

[PhilUK]

Thanks guys,  I will look into switch priorities.